On Thursday evening, food replacement startup Soylent halted sales of its Soylent 1.6 powder amidst reports that it was making customers sick. Two weeks prior, the company paused sales of its latest product, the Food Bar, after Gizmodo reported that several customers had experienced nausea, vomiting, “uncontrollable diarrhea,” and severe dehydration after consuming the bars. Some customers were admitted to the emergency room due to their symptoms.

In a blog post Thursday evening, Soylent revealed that while the company was reviewing what happened with Food Bars, it “noticed that a handful of consumers (less than 0.1%) who consumed Powder 1.6 over the past several months reported stomach-related symptoms that are consistent with what our Bar customers described.”Although the company wouldn’t say which ingredient is causing the illness, it has narrowed down its search, “given there are only a few ingredients that are specific to only [its] bars and Powder 1.6.”

Soylent is a case study in engineers thinking they’re smarter than everyone else, but aren’t.